Why do some women have flat, while other have firm, round butts? How do muscles grow? Detailed explanation and schedule of 4 weeks long butt exercise program together with illustration and video of each exercise. And much more in our 30 Days Booty Challenge. The new challenge starts on February 1st, so hurry up and get your book ;) p.s. use the code booty5off to get 5$ discount (we made this offer exclusively for our awesomest tumblr people, so don’t forget to use it!) :)